The U.S. has more teen moms than any other industrialized nation due to limited economic opportunities, according to a recent study.

If teenagers are on a "low economic trajectory," even increased access to birth control doesn't improve their chances of making it to 20 without getting pregnant, according to the NBER study, in which researchers analyzed national surveys on teen behavior.

Teen pregnancy rates were found to be especially high among poor people in communities with high levels of inequality.

U.S. teens are two and a half times as likely to give birth as compared to teens in Canada, around four times as likely as teens in Germany or Norway, and almost 10 times as likely as teens in Switzerland. Among more developed countries, Russia has the next highest teen birth rate after the United States, but an American teenage girl is still around 25 percent more likely to give birth than her counterpart in Russia.